In recent years, for the purpose of energy saving and downsizing, light-emitting devices (light-emitting diode (hereinafter referred to as “LED”) flashes) using a LED as the light source have been increasingly used as a light-emitting device for an image pickup camera. A well-known example of such light emitting devices is a light emitting device using a combination of an LED and a light flux controlling member (see, for example, PTL 1).
FIG. 1A is a sectional view of the light emitting device disclosed in PTL 1. As illustrated in FIG. 1A, light emitting device 10 disclosed in PTL 1 includes substrate 20, light source substrate 21, light source 30 including a light emitting element and a phosphor, and light flux controlling member 40. Light flux controlling member 40 is disposed on substrate 20 in such a manner as to face the light emitting surface of light source 30.
FIG. 1B is a sectional view of light flux controlling member 40. As illustrated in FIG. 1B, refractive fresnel lens part 41 and reflective fresnel lens part 42 are formed on one side of light flux controlling member 40. Each of Refractive fresnel lens part 41 and reflective fresnel lens part 42 has a plurality of concentrically formed annular protrusions. Refractive fresnel lens part 41 is formed at a position which faces light source 30. Reflective fresnel lens part 42 is formed around refractive fresnel lens part 41 in such a manner as to surround light source 30. In light flux controlling member 40, the surface on which refractive fresnel lens part 41 and reflective fresnel lens part 42 are formed functions as incidence region 43, and the surface on the side opposite to incidence region 43 functions as emission region 44.
In light-emitting device 10 illustrated in FIG. 1A, light emitted from light source 30 at a small angle to the optical axis is refracted in a predetermined direction by refractive fresnel lens part 41, and is emitted from emission region 44. On the other hand, light emitted from light source 30 at a large angle to the optical axis is incident on incidence surface 45 of reflective fresnel lens part 42, and emitted from emission region 44 after being reflected by reflecting surface 46 in a direction parallel to the optical axis of the light source. In this manner, light emitting device 10 disclosed in PTL 1 controls the distribution of the light emitted from light source 30 with use of light flux controlling member 40 including refractive fresnel lens part 41 and reflective fresnel lens part 42.
In addition, as a light flux controlling member including a reflective fresnel lens part, an inner lens of a light fixture for a vehicle and the like have been proposed (see, for example, PTL 2). In PTL 2, the use efficiency of light is improved by reflecting a part of the light incident on the reflective fresnel lens such that the light approaches the central axis side of the light flux controlling member.